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Date: Sat, 19 Feb 2011 16:41:04 +0100
From: kaber@...sh.net
To: davem@...emloft.net
Cc: netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH 1/2] netfilter: tproxy: do not assign timewait sockets to skb->sk
From: Florian Westphal <fwestphal@...aro.com>
Assigning a socket in timewait state to skb->sk can trigger
kernel oops, e.g. in nfnetlink_log, which does:
if (skb->sk) {
read_lock_bh(&skb->sk->sk_callback_lock);
if (skb->sk->sk_socket && skb->sk->sk_socket->file) ...
in the timewait case, accessing sk->sk_callback_lock and sk->sk_socket
is invalid.
Either all of these spots will need to add a test for sk->sk_state != TCP_TIME_WAIT,
or xt_TPROXY must not assign a timewait socket to skb->sk.
This does the latter.
If a TW socket is found, assign the tproxy nfmark, but skip the skb->sk assignment,
thus mimicking behaviour of a '-m socket .. -j MARK/ACCEPT' re-routing rule.
The 'SYN to TW socket' case is left unchanged -- we try to redirect to the
listener socket.
Cc: Balazs Scheidler <bazsi@...abit.hu>
Cc: KOVACS Krisztian <hidden@...abit.hu>
Signed-off-by: Florian Westphal <fwestphal@...aro.com>
Signed-off-by: Patrick McHardy <kaber@...sh.net>
---
include/net/netfilter/nf_tproxy_core.h | 12 +-----------
net/netfilter/nf_tproxy_core.c | 27 ++++++++++++---------------
net/netfilter/xt_TPROXY.c | 22 ++++++++++++++++++++--
net/netfilter/xt_socket.c | 13 +++++++++++--
4 files changed, 44 insertions(+), 30 deletions(-)
diff --git a/include/net/netfilter/nf_tproxy_core.h b/include/net/netfilter/nf_tproxy_core.h
index cd85b3b..e505358 100644
--- a/include/net/netfilter/nf_tproxy_core.h
+++ b/include/net/netfilter/nf_tproxy_core.h
@@ -201,18 +201,8 @@ nf_tproxy_get_sock_v6(struct net *net, const u8 protocol,
}
#endif
-static inline void
-nf_tproxy_put_sock(struct sock *sk)
-{
- /* TIME_WAIT inet sockets have to be handled differently */
- if ((sk->sk_protocol == IPPROTO_TCP) && (sk->sk_state == TCP_TIME_WAIT))
- inet_twsk_put(inet_twsk(sk));
- else
- sock_put(sk);
-}
-
/* assign a socket to the skb -- consumes sk */
-int
+void
nf_tproxy_assign_sock(struct sk_buff *skb, struct sock *sk);
#endif
diff --git a/net/netfilter/nf_tproxy_core.c b/net/netfilter/nf_tproxy_core.c
index 4d87bef..474d621 100644
--- a/net/netfilter/nf_tproxy_core.c
+++ b/net/netfilter/nf_tproxy_core.c
@@ -28,26 +28,23 @@ nf_tproxy_destructor(struct sk_buff *skb)
skb->destructor = NULL;
if (sk)
- nf_tproxy_put_sock(sk);
+ sock_put(sk);
}
/* consumes sk */
-int
+void
nf_tproxy_assign_sock(struct sk_buff *skb, struct sock *sk)
{
- bool transparent = (sk->sk_state == TCP_TIME_WAIT) ?
- inet_twsk(sk)->tw_transparent :
- inet_sk(sk)->transparent;
-
- if (transparent) {
- skb_orphan(skb);
- skb->sk = sk;
- skb->destructor = nf_tproxy_destructor;
- return 1;
- } else
- nf_tproxy_put_sock(sk);
-
- return 0;
+ /* assigning tw sockets complicates things; most
+ * skb->sk->X checks would have to test sk->sk_state first */
+ if (sk->sk_state == TCP_TIME_WAIT) {
+ inet_twsk_put(inet_twsk(sk));
+ return;
+ }
+
+ skb_orphan(skb);
+ skb->sk = sk;
+ skb->destructor = nf_tproxy_destructor;
}
EXPORT_SYMBOL_GPL(nf_tproxy_assign_sock);
diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
index 640678f..dcfd57e 100644
--- a/net/netfilter/xt_TPROXY.c
+++ b/net/netfilter/xt_TPROXY.c
@@ -33,6 +33,20 @@
#include <net/netfilter/nf_tproxy_core.h>
#include <linux/netfilter/xt_TPROXY.h>
+static bool tproxy_sk_is_transparent(struct sock *sk)
+{
+ if (sk->sk_state != TCP_TIME_WAIT) {
+ if (inet_sk(sk)->transparent)
+ return true;
+ sock_put(sk);
+ } else {
+ if (inet_twsk(sk)->tw_transparent)
+ return true;
+ inet_twsk_put(inet_twsk(sk));
+ }
+ return false;
+}
+
static inline __be32
tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
{
@@ -141,7 +155,7 @@ tproxy_tg4(struct sk_buff *skb, __be32 laddr, __be16 lport,
skb->dev, NFT_LOOKUP_LISTENER);
/* NOTE: assign_sock consumes our sk reference */
- if (sk && nf_tproxy_assign_sock(skb, sk)) {
+ if (sk && tproxy_sk_is_transparent(sk)) {
/* This should be in a separate target, but we don't do multiple
targets on the same rule yet */
skb->mark = (skb->mark & ~mark_mask) ^ mark_value;
@@ -149,6 +163,8 @@ tproxy_tg4(struct sk_buff *skb, __be32 laddr, __be16 lport,
pr_debug("redirecting: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
iph->protocol, &iph->daddr, ntohs(hp->dest),
&laddr, ntohs(lport), skb->mark);
+
+ nf_tproxy_assign_sock(skb, sk);
return NF_ACCEPT;
}
@@ -306,7 +322,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
par->in, NFT_LOOKUP_LISTENER);
/* NOTE: assign_sock consumes our sk reference */
- if (sk && nf_tproxy_assign_sock(skb, sk)) {
+ if (sk && tproxy_sk_is_transparent(sk)) {
/* This should be in a separate target, but we don't do multiple
targets on the same rule yet */
skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
@@ -314,6 +330,8 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
tproto, &iph->saddr, ntohs(hp->source),
laddr, ntohs(lport), skb->mark);
+
+ nf_tproxy_assign_sock(skb, sk);
return NF_ACCEPT;
}
diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c
index 00d6ae8..9cc4635 100644
--- a/net/netfilter/xt_socket.c
+++ b/net/netfilter/xt_socket.c
@@ -35,6 +35,15 @@
#include <net/netfilter/nf_conntrack.h>
#endif
+static void
+xt_socket_put_sk(struct sock *sk)
+{
+ if (sk->sk_state == TCP_TIME_WAIT)
+ inet_twsk_put(inet_twsk(sk));
+ else
+ sock_put(sk);
+}
+
static int
extract_icmp4_fields(const struct sk_buff *skb,
u8 *protocol,
@@ -164,7 +173,7 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
(sk->sk_state == TCP_TIME_WAIT &&
inet_twsk(sk)->tw_transparent));
- nf_tproxy_put_sock(sk);
+ xt_socket_put_sk(sk);
if (wildcard || !transparent)
sk = NULL;
@@ -298,7 +307,7 @@ socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par)
(sk->sk_state == TCP_TIME_WAIT &&
inet_twsk(sk)->tw_transparent));
- nf_tproxy_put_sock(sk);
+ xt_socket_put_sk(sk);
if (wildcard || !transparent)
sk = NULL;
--
1.7.2.3
--
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